The relatively high current carrying capacity of high-power semiconductor chips necessitates the conduction of the heat produced therein to an adjacent cold plate. The connection between the cold plate and the chip requires high thermal conductivity, an accommodation for small deviations from nominal distance and parallelism between the opposed surfaces of the chip and cold plate, respectively, and the connection must be inexpensive to manufacture and use. These needs have led to the development of flexible, extensible thermal conduction elements integrated to a semiconductor package to conduct heat from the chips to a cold plate, cover or cap which feature a plurality of thin flexible, interleaved leaf elements capable of spanning the gap between the chip or other semiconductor device and the cold plate while accommodating for gap variability and chip from parallelism between opposed surfaces of the device and cold plate. Such cooling devices integrated to a high power chip package are the subject matter of copending U.S. application Ser. No. 289,025 filed Aug. 3, 1981 by Louis Drucker Lipschutz, and assigned to the common assignee.
In that application, a cooling device functions as a thermal bridge element in a semiconductor package to conduct heat from the back side of solder bonded semiconductor devices or chips to a cold plate located in close proximity to the device. A first set of flat, thin, flexible leaf elements are held as a first unit with first spacer means spacing the first set of individual leaf elements such that a portion of the leaf elements project beyond the spacer means. A second set of flat, thin, flexible leaf elements, which have portions disposed in slidable overlapping relation to the first set of leaf elements, are maintained in position by second spacer means. Spring means function to bias the first and second units in outwardly extended relation. As such, the elements consist generally of a plurality of interleafed thin plates arranged so that the element is expandable and these leaf elements are also capable of adjusting while in intimate contact, even though the base surface may be tilted relative to the cap surface. Such elements exhibit extremely low thermal resistance.
While each cooling device unit functions effectively to transmit heat to the cold sink, the individual cooling devices are formed of a relatively large number of parts, may exhibit some difficulty in manufacture, and as such tend to be expensive.
It is, therefore, a primary object of the present invention to provide a highly economic and simplified, flexible, extensible, high thermal conduction, high power chip cooling device which is capable of meeting the high thermal load dissipation requirements of the rapidly advancing technology of high power integrated circuit chips.